A user equipment (UE) enters into an idle mode when its radio connection is released. Once in idle mode, if the UE needs to be reached by the network, the 3G and LTE standards define a procedure called paging. Paging involves broadcasting the UEs identity in the radio cells belonging to a set of eNodeBs or base stations grouped into tracking areas. Paging Messages are broadcasted over the location area code (LAC) for UMTS, routing area code (RAC) for GERAN, and tracking area code (TAC) for LTE area so that a Mobile Terminating Call may be answered. If the UE is present in one of the cells, it will respond to paging by performing a service request procedure. This results in the radio connection being re-established and the network becoming able to communicate with the UE for either control or data traffic.
Since many UEs in the LTE network are in idle mode at any given time, this equates to a high number of paging attempts going on a given network. A paging strategy is needed to reach the UE while reducing load and effectively utilizing paging resources.